This invention relates to a side-bar chain for chain drives, particularly for infinitely variable cone pulley transmissions. The articulations (chain pins) coupling the individual chain links together are constituted by pressure members accommodated in aligned apertures of the side bars forming the links. The opposite end faces of the pressure members transmit the frictional forces between pulley and chain. Further, the outermost (flanking) side bars of at least some of the chain links are combined into a brace by means of a transverse web straddling the individual side bars which are situated between the flanking side bars.
Side-bar chains of the above-outlined type are known in numerous constructions, such as disclosed in German Pat. Nos. 1,065,685, 1,119,065, 1,302,795 and 2,356,289. The side-bar chains may be of the dual side-bar coupling as disclosed, for example, in German Pat. No. 1,065,685 or of the triple side-bar coupling as shown, for example, in FIG. 14 of German Pat. No. 1,119,065. In case of a dual side-bar coupling, the pressure members are at a relatively large distance from one another as viewed in the direction of chain run (chain length) and may be formed, for example, as pairs of rocker pieces. The structure is relatively narrow in a direction transverse to the chain length. In contradistinction, in case of triple side-bar coupling, the chain dimension measured transversely to the chain length is relatively wide, while the distance of the pairs of rocker pieces from one another is relatively small which permits a reduction of the chain pitch (chain division). Further examples of such side-bar chains are described in U.S. patent application Ser. No. 285,869, filed July 22, 1981, naming Manfred Rattunde and Walter Schapf as inventors and assigned to the assignee of the present application.
In the side-bar chains outlined above, the brace formed in each instance by two side bars and the interconnecting transverse web serves to increase the anti-torsion stiffness of the chain and to so position the individual side bars straddled by the brace that solely the pulley discs and the articulations (chain pins) participate in the force transmission between the pulleys and the chain. By virtue of the wear in the articulations, side-bar chains without braces lose rapidly their initial stiffness which resists shearing and torsion forces. This results in an increased wear in the articulations. This occurrence, in turn, causes a further reduction in the anti-shearing and anti-torsion stiffness of the chain.
The known chain braces, however, as compared to the individual side bars have a different behavior of deformation in the tension force transmitting zone, where the side bars forming the brace are joined to the transverse web. This is so, because at those locations the components have an increased stiffness. As a result, for a given identical force-application, in those locations only a small deformation can take place, whereby between the individual side bars and the side bars forming the brace a non-uniform force transmission and thus a non-uniform utilization of the material occurs. Particularly in case of excessive loads, the side bars forming the braces may thus be damaged or destroyed due to excessive tensions.
It is a further disadvantage of side bars forming an integral part of known chain braces that the pressure members, such as rocker pieces, are, in the zone of the side bars forming the brace, that is, at their ends, pressed towards one another by the brace-forming side bars with a greater force than in the remaining zones where they have a theoretically uniform linear engagement with the side bars which they traverse. This increases the load on the rocker pieces precisely at locations where they are stressed the most due to the frictional force transmission. This results at those locations in significant wear traces or crumbling and therefore a power transmission which would be otherwise warranted by the type of chain material, cannot be fully utilized in practice.